Heat exchanger



Feb. 16, 1943. A, s, LlMPERT 2,310,970

HEAT EXCHANGER Filed May 28, 1941 Patented Feb. 16, 1943 UNITED STATESPATENT OFFICE HEAT EXCHANGER Alexander S. Limpert, Bay Shore, N. Y.

Application May 28, 1941, Serial No. 39517 3 Claims.

This -inventior relates to heat exchangers, more especially condensersfor refrigeration and air conditioning purposes and has for itsparticular objects the provision of a highly efiicient, extremely sturdyand compact device which can be easily cleansed to remove externallydeposited dust and other sediment and which is simple and cheap tomanufacture especially since it requires but a relatively small amount,by weight, of metals of high conductivity in its construction.v Furtheradvantages of my invention are hereinafter set forth.

Heretofore, as I am well aware, it has been proposed to scuff or strikeup the surface of a condenser tube to form a series of spirally disposedrigid tapered spaced teeth which are of relatively thick cross sectionat the base thereof. The total weight of metal in such teeth is rel-"atively large as compared with the Weight of the filaments employed inmy improved heat exchanger and furthermore, such teeth do not lntersectand contact with each other intermediate the ends thereof as do theaforesaid filaments of my heat exchangers buton the contrary, areseparated from each other throughout the entire length thereof by airgaps of gradually increasing extent from the base to the tip of eachtooth.

Certain preferred embodiments of my invention are fully set forth in thefollowing detailed description and drawing forming a part thereof inwhich latter Figure 1 is an elevation, partly in section, of a condenserforrefrigeration or air conditioning purposes embodying my invention;

Fig. 2 is a fragmentary side elevation and Fig. 3 an end elevation ofthe tinsel garland element of such condenser, isolated and prior tobeing wound on the tubular support therefor,

Fig. 4 is a fragmentary side elevation and Fig. 5 is an end elevation ofsuch garland, isolated from its support showing the position of 'thefilaments in the garland after the same have folded on themselvespreparatory to winding the garland on the supporting tubing;

Fig. 6. is an enlarged, fragmentary, vertical cross section and Fig. 'lis an enlarged fragmentary longitudinal section of one reach of tubingof such condenser wherein tinsel garland .is applied both externally andinternally to such condenser and which form of condenser is especiallyadapted for cooling or heating non-condensable gases; and

Fig. 8 is a perspective view of the wiper slide employed for cleaning insitu the externally applied garland of the condenser.

Referring to the construction illustrated in the drawing, the referencenumeral I designates the looped tubing of a condenser for refrigerationpurposes, 2 the various supporting bars thereof which are brazed orwelded to the opposing lateral extremities of such tubing; and thereference numerals 3 and 3' designatel external and internal radiationelements of high heat conductivity carried thereby, the sameconstituting so-called tinsel garland, which as is well known comprisesa stranded wire core a to which are anchored a multiplicity ofindividual looped filaments b. Usually the core wires are reinforced bya covering of cotton threads to facilitate the drawing of the fine corewires through the tinsel making machines by relieving the strain on suchwires during their passage therethrough. Each filament comprises anarrow fiat metal strip, centrally folded, which is desirably composedof copper plated with silver, such strips being desirably of a totallength of about 3", extremely thin, but about 0.002 to 0.008 inthickness and but about 11g" wide, for example. These filaments are ofremarkable flexibility and sufficient resiliency to spring back to theiroriginal position when distorted temporarily. The garland element 3 isspirally Wrapped on the tubing of the condenser, after rst bending thelooped filaments outwardly in the manner illustrated in Figs. 4 and 5and, when so wrapped certain filaments will intersect'or interlace withother adjacent filaments thereby establishing a multiplicity of contactpoints therebetween which materially enhance the heat exchange betweenthe filaments and the tubing on which the garland is wrapped.

A wiper slide 5 of metal or plastic material is preferably removablymounted on said tubing.

. This slide has a series of holes 6 drilled therein each intersected bya slot 1 which is of sufiicient width to admit of the tubing beinginserted therethrough into the holes 6. Each hole is of suiiicientlygreater diameter than the external diameter of said tubing plus doublethe thickness of the wrapped filament a to admit of the freereciprocation of' the slide through the garland when it is desired tocleanse the same.

In the internal radiation element 3 the tinsel garland has the filamentsthereof compressed and bent rearwardly as illustrated in Figs. 1 and 7.This internal radiation element is preferably only employed for heatexchangers wherein noncondensable gases are circulated since in the caseof condensable vapors and liquids it is desirable to have the conduitsof the tubing entirely unobstructed to facilitate the rapid circulationof the liquids therethrough.

Preferably, prior to the application of the tinsel garland to thetubing, the latter is coated with metallic paint, such as aluminum paintor some heat conductive adhesive, as designated by the reference numeralc, as the same not only tends to anchor or set the cores of the tinselgarland in situ on the tubing but also forms a heat conductive bondbetween the tinsel garland and the tubing since it eliminates air gapsbetween the tinsel core and the tubing besides enhancing, due to its owninherent heat conductivity, the heat transmission between the metal coreof the garland, particularly where cotton threads are incorporatedtherewith, and the metal surface of the tubing because the cottonthreads soak up the metallic binder and thereby their heat conductivityis substantially increased.

The wiper slide 5 which is adapted to be normally positioned at one endof the condenser serves as an effective cleanser therefor since itmerely is necessary to slide the same back and forth over the tinselgarland in order to substantially completely eliminate any dust or othersediment deposited in the garland and, due to the inherent resiliency ofthe individual filaments of such garland, the same immediately resumetheir original position once they are relieved from the influence of theslide. Furthermore the operation of cleansing of such garland byreciprocation of the slide through the filaments thereof does not haveany deleterious effect upon the filaments du'e to their remarkabledurability and ready flexibility and as a matter of fact, unless thefilaments were unusually durable and flexible so as to admit of therapid sliding to and fro of either the wiper slide or the fingers, whenenveloped thereby, it would be diidcult if not impossible -toeffectively cleanse the filaments with the consequence that dust andkother sediment would gradually collect thereon and eventually wouldmaterially decrease the efficiency of the garland as a heat radiatingmedium.

The aforesaid tinsel garland possesses many advantageous characteristicswhich peculiarly adapt the same for use in heat exchangers as theradiation element thereof, for example due to the extremely smalldimension thereof both as regards thinness and width, the same can beplated at an almost negligible expense with metallic silver which metal,as is well known, possesses a remarkably high co-efiicient of heatconductivity. Such plating also tends to increase the elasticity of thefilaments thus insuring the quick restoration thereof to their originalposition when displaced longitudinally of the tubing during thecleansing thereof as aforesaid with a wipei` element or with the hand.Also the fact that the filaments project outwardly from the tubing in aplurality of different planes, the multiplicity of points ofintersection thereof with adjacent filaments enhances the totalcoeflicient of heat conductivity of the garland radiation element,Again, the cheapness of assembly of the condenser unit is particularlyimportant since it is but a simple matter to Wind the tinsel garland onthe tubular support either by hand or simple winding equipment, such asa bobbin rotatably mounted on a revolving arm, and therefore no dies orcomplicated machinery are required in order to rapidly manufacture thecomplete condenser on a. large production scale. As a consequence, suchcondenser can be manufactured by a manufacturer of refrigeration or airconditioning equipment since not only, as above stated, are no specialdies or complicated machinery required, but no highly skilled labor needbe employed in such production owing to the ease of applying the garlandto its tubular support.

While in the preferred form of condenser illustrated herein the tubularsupport comprises tubing having a plurality of return bends formedthereon which form parallel reaches of such tubing obviously, ifdesired, the tubing could be wound as a pancake spiral and with thecoils thereof spaced sufficiently apart to admit of the application oftinsel garland thereto. Also, it is, of course, understood that thecondensers may be constructed of several parallel reaches of tubing eachwound with garland.

The aforesaid condenser construction is remarkably efficient, beingequal or even superior to condensers formed from tubing having metallicfins applied thereto, such as the honeycomb type of condenser forexample, which fin type of condenser is almost invariably manufacturedby concerns specializing therein because of the complicated machineryand highly specialized training on the part of the operators required insuch manufacture.

While in the tinsel garland such as used for decorative purposes and thelike and which is also suitable for use in my condenser construction,cotton threads or cords are wrapped around the metal core thereof, forthe reasons heretofore explained, nevertheless other garland, ifdesired, may be employed, such as the type known as printers garland,which has thicker and longer filaments than those used in decorativegarland although, due to the excellent heat conductivity, cheapness anddurability of the ordinary garland, such as used for decorative purposesas above specified, particularly during the Christmas season, I havefound that the same is especially desirable for use in the manufactureof condensers and radiators such as aforesaid.

Various modifications of the above described heat exchanger constructionmay be made without departing from the spirit of my invention asembraced within the scope of the appended claims.

Having thus described my invention, what I claim is:

1. In a heat exchanger, the combination comprising a tubular supporthaving a rope of tinsel garland wound thereon and secured thereto.

2. In a heat exchanger, the combination comprising a tubular supporthaving heat radiation means spirally wound thereon, which comprisesessentially tinsel garland having a metal core and a multiplicity offlat, extremely thin metallic filaments extending outwardly therefrom ina plurality of different planes, such filaments being elastic, highlyflexible and of a thickness of the order of between 0.001" and 0.01.

3. In a heat exchanger, the combination comprising a tubular conduit forfluid having a rope of tinsel garland spirally wound thereon, saidgarland having a stranded core and a multiplicity of iilamentary,metallic heat radiating elements projecting outwardly therefrom, saidcore being united in good heat conductive relation to the external wallof said tubing by a metallic bonding medium.

ALEXANDER S. LIMPERT.

